Tank stabilizer for ships



Oct. 7, 1969 F. v. A. PANGALILA 3,470,840

l TANK STABILIZER Fon saws Filed May '7, 1968 5 Sheets-Sheet l FRANS v. A. PANGALILA Oct. 7, 1969 F. v. A. PANGALILA 3,470,340

TANK STABILIZER FOR SHIPS Filed May 7, 196B 5 SheetsfSht 1111111111111//lrll/l//I//l[r11/111111111111 [III/l l/ll 20 LA 5a 32 244' u f f I n l v f Ill/[IIIIFTII [Ill/llllllll//Il/lll lll/l [lll l l l l f 1111/11/1111Il11171/111111//1/11/1111 1 11 111 111/ ll 36 fw r 111 11111/ [lill/[Inl] 1l l 1111111 11 1 l J 1 Irl! /1/ ll 1111/1/ lll/ll l 1111 gef/ v INVENTOR FRANS V. A. lPANGALILA ATTORNEYS v Filed 7, 1969 F. v. A. PANGALILA TANK STABILIZER FOR SHIPS May 7. 1968 3 Sheets-Sheet 11lll/1III/l/lIll/llllllll//lllll//Il/l/l ll lll/[II] III/7] mvENrQR FRANS V. A. PANGALILA ATTRNEY` United States Patent 3,470,840 TANK STABILIZ R FOR SHIPS Frans V. A. Pangalila, Matawan Township, NJ., assignor to Fiume Stabilization Systems, Inc., Hoboken, NJ., a corporation of New Jersey Filed May 7, 1968, Ser. No. 727,227 Int. Cl. B63b 43/06 U.S. Cl. 114-125 9 Claims ABSTRACT OF THE DISCLOSURE A free surface tank stabilizer for ships having internal members dening outboard wing tanks and an aperture extending athwartships to control and damp the passage of liquid from one wing compartment to the other.

BACKGROUND It is generally accepted in the art that the recent advance in the technology of passive tank stabilizers has reached a point where highly satisfactory results are obtained with free surface tank stabilizers but, efforts continue in the design of tank stabilizers in which the internal tank geometry and internal structure permits a greater range of etiicient tank operation for a greater range of ship loading characteristic. Particular problems are encountered in tank stabilizers for long period ships in which the dynamic amplification factor of the tank is relatively small.

One approach to the solution of the above problem has been a tank design which, by virtue of its tank shape, is designated to remain in resonance with the ship rolling anywhere within a range of frequencies. See, for example, German Auslegeschrift 1,253,091, dated Oct. 26, 1967. For this tank the liquid has different distances to travel and consequently, because the speed is generally constant, the tank has different periods. A result of this would be that the phase curve of such a tank is flatter than the phase curve of a rectangular open tank. Although tanks of this design may remain in the tuned condition over a range of frequencies, nevertheless, the stabilizing moment magnitude is greatly reduced to the extent that tank eiciency is significantly undermined.

It is a primary purpose of the present invention to solve the aforementioned problem without the disadvantages encountered in conventional tank designs by providing a new and improved passive stabilization system employing the free surface principle. One example of the invention includes an elongated generally rectangular tank arranged athwartships and having internal members defining a pair of opposite wing tanks such that one wing tank communicates with the interconnecting tank portion through the aft part of the tank and the other wing tank communicates with the interconnecting portion through the forward part of the tank. Members forming a communicating aperture are so arranged that the tank liquid transferring in response to the ships roll passes somewhat in the fore or aft direction and then into the respective wing tank. If desired, the tank can be activated by incorporating an impeller or pumping unit in the vicinity of the center aperture or alternatively the aperture can be adjustable in cross section so as to control the amount of hydrodynamic damping imparted to the tank liquid. With this latter arrangement, the tank liquid level can be such that the liquid volume is greater than that needed for tuning the tank thus increasing the stabilizing moment magnitude.

Tanks according to the invention will have the full waterplane inertia as well as all possibilities from an open tank to a very restricted tank. Thus with a controlled aperture capability for a certain liquid level, the period of the tank can be changed to a very fast open tank, to a slow restricted tank. Of course tuning can be accomplished also by changing the tank liquid level. The configuration according to the invention will have two basic resonant periods, and by adjusting the connection between the two parts, this period can be favorably iniluenced. The phase curve has a ilat characteristic which will reduce the possibilities of destabilization of a ship rolling outside of its resonant frequency.

The primary object of the invention is to provide a new and improved tank stabilizer of the type described that provides the advantages and solves the problems outlined above.

Other further objects of the invention will become apparent with the following detailed description when taken in view of the appended drawings in which like character references designate like structure and wherein:

FIGURE l illustrates a typical transverse section through the hull of a ship embodying the present invention.

FIGURE 2 is a top plan of a tank stabilizer according to the invention with the top removed.

FIGURE 3 is a longitudinal vertical section through the tank taken along line 3-3 of FIGURE 2.

FIGURES 4, 7, 8 and 9 are top plan views of four additional embodiments of the invention, respectively.

FIGURES 5 and 6 are similar views to 2 and 3 respectively, illustrating a still further embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS Referring to the figures, the tank 12 according to the present invention is arranged in a ship generally indicated as 10 with its long dimension extending athwartships and preferably located between two decks which serve as the top and bottom of the tank 12. A liquid body 14 distributed throughout tank 12 partially iills the same and the tank top 16 is suiciently above the liquid level so as to provide an air space above the liquid throughout the tank. In accordance with the principles disclosed in U.S. Patent 3,054,173, the liquid level may be changed in the tank to adjust the natural period of the tank liquid oscillation.

With reference to FIGURES 2 and 3, one embodiment of the invention comprises a pair of upstanding bulkheads 18 and 20 extending from opposite fore and aft walls of tank 12 towards the longitudinal center line of the tank. Bulkheads 18 and 20 cooperate with the end walls of the tank 22 and 24 to form wing tanks and a central compartment which communicates with the wing regions.

Additional members or bulkheads 30 and 32 divide the center region into fore and aft channels communicating with opposite wing tanks. The inboard ends of said members 30 and 32 are spaced from each other to define aperture 34 through which the tank liquid passes in response to the rolling of the ship. If desired, more than one aperture 34 can be formed by members 30 and 32 and extending horizontally or vertically in the tank (see for example the embodiment of FIGURE 9). For the fixed aperture arrangement depicted in FIGURES 2 and 3, the dimensioning of aperture 34 should be related to the overall tank size, moment desired from the shifting tank liquid and anticipated loading conditions of the ship. Since the tank operation in this embodiment is controlled by adjusting the liquid level, the size of aperture 34 should accommodate generally the average or most frequently encountered liquid level.

The tank liquid comprises any suitable medium such as fresh water, sea water, reserve fuel, bunker oil, or any other type of liquid or liquid-solid suspension.

In operation, the tank liquid shifts from one wing tank toward the other in response to the rolling action of the ship and imparts to the ship a stabilizing moment in opposition to the inboard energy causing the ship to roll. Thus, the stabilizing moment generally lags the rolling of the ship by a factor of about 90. As one side of the ship lowers, the liquid in the center channel communicating with the lowering wing tank quickly flows toward that side of the ship and in this sense one half of the tank operates as a fast tank Whereas, by virtue of the members 30 and 32, the other half of the tank operates under a damped condition and continues to supply liquid to the opposite side of tank 12 so long as that side of the tank remains below the horizontal. As the ship passes through the righted position, opposite flow conditions will occur. This action continues so long as the ship continues to roll.

Another embodiment of the invention illustrated in FIGURE 4 includes an apparatus generally indicated as 36 and schematically shown as a rotating plate valve to selectively adjust the cross sectional open area of aperture 34. It will be understood that any suitable type of apparatus such as sliding rail mounted doors or valves, flap valves or hydraulically operated equipment can be used in place of or in conjunction with the illustrated rotating door which is disclosed by way of example. In this arrangement, the amount of hydraulic damping imparted to the transferring liquid is controllable and the overall tank 12 operates as a fast or slow tank depending upon the position of door 36. In addition, the tank can be completely deactivated in the event it becomes necessary or desirable by fully closing the door.

The present invention also lends itself to activation as illustrated in embodiment of FIGURES 5 and 6 in which there is installed an electrically operated impeller unit or pump 38, preferably controlled by electronic roll sensing equipment (not shown) now standard in the art. The activated system as shown has particular utility on ships with low roll amplification factors, say below 5. The system of FIGURES 5 and 6 operates as described above with unit 38 being driven to enhance liquid transfer during apparent parts of the roll cycle. If desired, additional openings 40 can be provided to increase Volume flow.

Still further embodiments of the invention are illustrated in FIGURES '7 and 8. In the system of FIGURE 7, bulkhead members 46 extend outboard and toward the tank centerline to increase the wing tank capacity. The system depicted in FIGURE 8 includes additional members 48 and S0 forming an additional constricted opening S2 preferably from top to bottom of the tank at the threshold of each wing tank to further damp the liquid thereat and permit a greater opening at 54 in wall 53 connected to walls 50. Operation of these systems are substantially the same as described above.

Other and further modifications can be made to the examples disclosed herein without department from the spirit and scope of the invention.

What is claimed is:

1. A free surface roll stabilization tank for ships comprising internal members extending from opposite fore and aft walls and terminating short of the other such wall to define wing tanks and a communicating intermediate tank compartment and additional internal members extending generally athwartship in the intermediate compartment forming an aperture communicating one wing tank and aft part of the intermediate compartment with the other wing tank and forward part of the intermediate compartment and a liquid body partially filling the tank, and means provided to permit unirnpeded passage of air over the liquid body throughout the tank.

2. The stabilization tank according to claim 1 wherein said members and additional members are connected and formed to cause a significant forward or rearward liquid 4movement through the aperture in response to the ships rolling so as to impart hydraulic damping thereto and causing the tank liquid to lag the ships roll.

3. The stabilization tank according to claim 2 where in the aperture extends above and below the static tank liquid level.

4. The stabilization tank according to claim 2 wherein the first mentioned members extend perpendicular from the wall to which it is connected and the additional members extend toward each other from said first mentioned members.

5. The stabilization tank according to claim 2 wherein said first mentioned members extend outboard as well as respectively fore and aft.

6. The stabilization tank according to claim 2 wherein adjustable means are provided to selectively control the effective open area of said aperture and thus control the amount of damping imparted to said tank liquid.

7. The stabilization tank according to claim 2 further comprising members defining constricted openings at the threshold between each wing tank and the associated fore or aft section of the intermediate compartment.

8. The stabilization tank according to claim 2 wherein the liquid pumping means is arranged in the tank below the static liquid level to pump the tank liquid from one fore or aft intermediate compartment section to the other, and thereby activating the tank.

9. The stabilization tank according to claim 2 wherein said additional members form more than one such aperture.

References Cited UNITED STATES PATENTS TRYGVE M. BLIX, Primary Examiner 

